|Image 1: Bought in bulk, grape-seed extract is actually reasonably cheap… and it does not even taste as awful as some other herb / seed extracts 😉|
After initially being hailed as the yet another anti-oxidant panaceum, grape-seed extract (GSE) has been displaced by newer, fancier “superfoods” from the headlines of the major health and wellness newscasters. Therefore, even you, as a highly self-educated student of the SuppVersity could have missed out on a handful of recently released studies which reported antiviral effects of GSE (Su. 2011) and confirmed its ameliorative effect on diet-induced obesity (Ohyama. 2011) and (high) fructose-induced insulin resistance (Meeprom. 2011). Moreover, a meta-analysis of nine controlled with more than 300 human subjects and daily doses ranging from 250mg to 2,000mg of GSE, which was published in the Journal of the American Dietetic Association (Feringa. 2011), found that …
[b]ased on the currently available literature, grape seed extract appears to significantly lower systolic blood pressure and heart rate, with no effect on lipid or CRP levels.
These results suggest that we (at least some of) the beneficial health effects that have been observed in rodent studies actually translate to human beings – something we cannot (yet?) say for some of the next generation “panacea” 😉 This is also important in view of the significance of the results GSE-administration had on exercise-induced oxidative stress in a more recent study by scientists from the universities of Konya and Dicle in Turkey (Belviranli. 2011), which was published in the latest issue of the British Journal of Nutrition.
The experiments were carried out with 64 adult male Sprague Dawley rats who were randomly assigned to one of the following six groups:
- sedentary control (C, n=10),
- chronic exercise control (CEC, n=11),
- acute exercise control (AEC, n=11),
- GSE-supplemented control (GC, n=10),
- GSE-supplemented chronic exercise (GCE, n=11), and
- GSE-supplemented acute exercise (GAE, n=11)
The rats in the treatment groups received a standardized GSE extract containing 54% dimeric, 13% trimeric, 7% tetrameric and <5% monomeric proanthocyanidines and undisclosed amounts of cathechines and oligomeric proanthocyanidines, at a daily dose of 100mg/kg body weight in their drinking water for 6 weeks.
|Image 2: Click here to learn how to calculate human equivalent doses (HED)|
Rat to human equivalent dosage calculation: If you have already read my dissertation on how to calculate the so-called human-equivalent-dose (HED), you will probably already have whipped out your calculator and are just about to type “100mg times the K-value for rats, which is 6; divided by the K-value for humans, which is 37” … and what does your calculator tell you? Correct! The HED of 100mg/kg GSE in rats is 16.33mg/kg – in other words, if you weigh 80kg you will have to take roughly 1,300mg of grape-seed extract per day to mimic the dosage that was used in the study.
The dosage, according to the scientists, was chosen because it had elicited beneficial anti-oxidant effects in previous studies on alloxan induced diabetes (El-Alfy. 2005) and age-related oxidative damage (Balu. 2006). And, as Belviranli et al. had suspected, it exhibited similar protective effects against the oxidative stress triggered by both chronic, 5x a week treadmill exercise at 25m/min for 45 minutes, as well as, acute running on the treadmill at 30m/min until exhaustion.
|Figure 1: Effects of acute or chronic exercise and grape seed extract (GSE) supplementation on plasma malondialdehyde (MDA) levels (data calculated based on Belviranli. 2011).|
As you can see in figure 1, administration of 100mg/kg grape-seed extract per day augmented the beneficial effect of 6 weeks of chronic exercise on muscle MDA levels (-37% vs. -18% in the control group) and ameliorated the acute +22% increase in MDA levels due to increased lipid peroxidation during exhaustive treadmill running.
|Figure 2: Effects of acute or chronic exercise and grape seed extract (GSE) supplementation on plasma nitric oxide (NO) levels (data calculated based on Belviranli. 2011).|
GSE supplementation also increased the expression of nitric oxide (NO in plasma; on average +25%) in all animals (cf. figure 2). Moreover, GSE ameliorated the increase in xanthine oxidase and adenosine deaminase activities due to acute exercise and triggered an overall increase in antioxidant enzyme activities.
So, even if your favorite anti-aging and health (onilne-)magazine or vendor appears to have forgotten about grape-seed extract. For a physical culturist like you and me, it may yet well be worth to (re-)include the extract from the seeds of the fruits of Vitis vinifera, which are a particularly rich source of vitamin E, linoleic acid and, most importantly, oligomeric proanthocyanidins, into our supplement regimen. And if the current study does not convince you, it may help, if I remind you of the 2006 study by Kijima et al. who were able to show that GSE due to its anti-aromatase activity can suppress tumor growth in a breast cancer model (Kijima. 2006) … ah, and before I forget: don’t be stupid and buy over-priced caps. Use google and find yourself a source of bulk grape-seed extract – don’t worry the taste is not all too bad 😉